Propane dehydrogenation kinetics on supported Pt catalyst

• A comprehensive kinetic model for PDH main and side reactions and steam reforming was composed.
• Catalyst deactivation was modeled in presence of steam.
• Catalyst deactivation can be significantly suppressed with P < 5 bar, with 10% steam at feed.
• Pellet diffusion effects on activity and selectivity are small; the effect on coking is significant.
• Rate of deactivation correlates with carbon build up on the surface

A kinetic model of propane dehydrogenation on a Pt,Sn/Mg(Al)O is presented, accounting for product distribution due to main and side reactions, for deactivation rates and for diffusion resistance. Parameters were estimated from steady state experiments at varying pressure and from temperature-programmed experiments, and are compared with previous models on similar catalysts and with published computed results. Steam was added to slow coke formation, leading to some steam reforming. The rate of deactivation was shown to correlate with carbon build up on the surface, which was determined from the selectivity to carbon.Application of the model to design a Pd-membrane reactor suggests that pressure should be kept below 5 bar and steam around 10% in feed, while pellet size affects mainly the selectivity while the effect on conversion is small. While the main reaction is fast, side reactions are not negligible, especially under conditions of a membrane reactor, but selectivity to propane can be maintained about 95%.

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